Many scientific, engineering, military, and other technologies seek to identify the type of an object that is hidden from view. For example, an object may be buried in the ground or be underwater, obscured by cloud cover, and so on. Some technologies detect the presence of buried objects such as landmines in a roadway or a field for military or humanitarian purposes. Such technologies may use ultra-wideband ground-penetrating radar (“GPR”) antennas that are mounted as a linear array of sensors on the front of a vehicle that travels on the roadway or across the field. The antennas are directed into the ground. GPR systems can be used to detect not only metallic objects but also nonmetallic objects whose dielectric properties are sufficiently different from those of the soil. When a radar signal strikes a subsurface object, it is reflected back as a return signal to a receiver. Current GPR systems typically analyze the strength or amplitude of the return signals directly to identify the presence of the object.
Once a subsurface object is detected, it can be helpful to distinguish between objects of different types or classes. For example, a GPR system may detect the presence of both buried landmines and underground utility structures. If it cannot be determined whether a detected object is a landmine or a utility structure, then significant time and resources may be used trying to manually determine the type of the detected object. Although some approaches have had some success in distinguishing objects, it would be helpful if the accuracy of the process of distinguishing types of objects could be improved.